CD4 and influenza: In the context of SARI surveillance target at influenza, a possible explanation for our late detection relies on the fact that immunosuppressed and critically ill patients there seems to be prolonged viral shedding.40 The median CD4 cell count in this study population was 80 (24–274) cells/mm3 and the proportion of patients with undetectable viral load was 25% despite 80% being exposed to ART.